HH44 DE Harvester Head Caterpillar

ReferenceRefer to Testing and Adjusting, "Preparation for Troubleshooting".

When you diagnose a problem in the electrohydraulic system, a visual inspection of the system is the first step. Perform the following inspections prior to testing or troubleshooting:

Hydraulic System

1. Depress the vacuum relief valve to relieve hydraulic oil tank pressure on units equipped with pressurized tanks. Check the oil level in the hydraulic oil tank.

   ReferenceIn order to release the hydraulic pressure for the whole machine refer to Testing and Adjusting, RENR7295, "Hydraulic System Pressure - Release" for track carriers.

2. Look for air in the hydraulic tank oil immediately after the engine is stopped. Use a clear container to obtain a sample of the oil. Look for air bubbles in the oil.

3. Remove the hydraulic oil filters and look for particles in the filter elements. A magnet will separate ferrous particles such as iron and steel from the nonferrous particles such as aluminum and rubber.

4. Check for flow restrictions in all oil lines. Flow restrictions include acute bends in the oil lines, clamps that are not installed correctly, and physical damage to hoses and to lines. Check all connections for damage and for leaks.

5. Check that all components are securely mounted to the machine.

Electrical System

Intermittent electrical problems are often caused by poor connections. Use the following checks as a guideline for inspecting connectors:

1. Check the mating fit of the connectors.
   • Ensure that the connector pins and the connector receptacles are aligned correctly.

   • Ensure that the Deutsch connectors are plugged in to the solenoid all the way.

2. Check the wires at the connectors.
   • Ensure that the wires do not enter the back of the connector at an angle.

   • Ensure that each wire is properly crimped into the proper connector contact.

   • Ensure that each connector contact is properly locked into the connector body. When the connector contact is locked properly, the contact or the wire cannot be pulled out of the connector body without excessive force.

3. Check each wire for nicks and for signs of abrasion in the insulation.

4. Check for moisture at the connector. The following conditions are possible causes of moisture:
   • Connector seals are damaged or missing.

   • Plugs for the wire holes are loose or missing.

   • Wires do not enter the back of the connector straight. If the wires enter the connector at an angle, there may not be a good seal between the connector and the wire insulation.

   • Moisture from other connectors with poor seals may have traveled inside the wire insulation.

5. Check for electrical contacts that are dirty or corroded.
   • Clean the contacts with a cotton swab or with a soft brush.

6. Check the condition of each connector pin and each connector receptacle.